Academy of Forensic Science, Shanghai, China.
Academy of Forensic Science, Shanghai, China.
Forensic Sci Int. 2022 Jul;336:111321. doi: 10.1016/j.forsciint.2022.111321. Epub 2022 Apr 27.
As a custom in China, a visible fingerprint pressed with red seal ink on a signature represents personal confirmation of a document. This custom makes ink fingerprints important evidence for individual identification in the forensic practice of questioned document examination. Recently, forged ink fingerprints using stamps or silica gel fingerprint models have emerged. Consequently, detecting and profiling the pattern of biological substances in visible fingerprints on questioned documents is crucial to prove that a fingerprint was imprinted by its real owner. To solve this problem, a desorption electrospray ionization mass spectrometry (DESI-MS) method was developed to detect the biological substances in ink fingerprints on paper. In the positive ion mode, more signals were detected, but the interference from the seal inks could not be ignored. In the negative ion mode, the ion detected in the sweat latent fingerprints at m/z 187 presented high chemical specificity for MS imaging. It was most likely a borate compound in human sweat. Using this biomarker, the fingerprint pattern was successfully profiled and the hand-imprinted fingerprint was clearly distinguished from the stamp-imprinted one. This method can help in determining the authenticity of ink fingerprints on questioned documents in forensic practice.
在中国有一种习俗，就是在签名上用红色印章油墨按压可见指纹，以代表对文件的个人确认。这种习俗使得油墨指纹成为文件检验中个人识别的重要证据。最近，出现了使用印章或硅胶指纹模型伪造油墨指纹的情况。因此，检测和分析可疑文件上可见指纹中生物物质的模式对于证明指纹是由其真正所有者按压形成的至关重要。为了解决这个问题，开发了一种解吸电喷雾电离质谱（DESI-MS）方法来检测纸张上油墨指纹中的生物物质。在正离子模式下，可以检测到更多的信号，但不能忽视印章油墨的干扰。在负离子模式下，在 m/z 187 处检测到的汗潜指纹中的离子对 MS 成像具有很高的化学特异性。它很可能是人体汗液中的硼酸化合物。利用这种生物标志物，可以成功地对指纹图案进行分析，并清楚地区分手印指纹和印章指纹。该方法有助于确定法医实践中可疑文件上油墨指纹的真实性。
